Vought XF8U-1 Crusader

Last revised December 26, 2007

The Vought F8U Crusader was the first Navy aircraft capable of sustained
supersonic flight and was the first Navy fighter capable of exceeding
1000 mph in level flight. A total of 1261 Crusaders were built. Forty-five years
after the first flight of the prototype, the Crusader still serves
with the French Navy.

In September of 1952, the Navy issued a Request For Proposals for a new
carrier-based day fighter capable of Mach 1.2 at 30,000 feet and Mach
0.9 at sea level, an initial climb rate of 25,000 feet per minute, and
a landing speed of only 100 knots. The RFP was issued to McDonnell,
North American, Douglas, Convair, Lockheed, Grumman, Vought, and
Republic. Of these, only Douglas, McDonnell, Grumman, and Vought had
any real experience with carrier-based aircraft.

The Chance Vought company of Dallas, Texas went to work on their
proposal. At that time, Chance Vought was a part of the United
Aircraft Corporation. Vought engineer John Russell Clark led the
design team. He had worked on the F6U Pirate and the F7U Cutlass.

A total of 21 proposals were submitted from eight different aircraft
companies. The most viable proposals were deemed by the Navy to be
the Grumman XF11F-2 (a version of the F11F Tiger powered by the
General Electric J79), the McDonnell F3H-G (a twin-engined adaptation
of the F3H Demon), and the North American "Super Fury" (a navalized
F-100), plus the Vought submission, which was given the company
designation V-383.

In May of 1953, the Navy selected the Vought V-383 as the winner of
the competition. The Navy at that time ordered several mockups and
wind tunnel test models. The designation XF8U-1 was assigned. At the
same time, the reconnaissance version, V-392, was also ordered under
the designation F8U-1P.

The Vought proposal was designed around the Pratt & Whitney J57-P-11
axial flow turbojet, which offered 10,900 lb.s.t. dry and 14,500
lb.s.t. with afterburning. The most unusual feature of the Vought
design was the use of a high-mounted swept wing whose angle of
incidence could be varied in flight. During takeoff or landing, the
angle of incidence could be increased by seven degrees, which enabled
the wing to retain a high-angle of attack during takeoff and landing,
and yet enabled the fuselage to remain fairly level for better forward
visibility. The variable-incidence wing was operated by positioning
and locking handles inside the cockpit. When the wing is raised, the
center section protrudes into the airstream, thereby acting as a large
speed brake. The ailerons and the entire wing leading edge surfaces
were interconnected and were automatically lowered to 25 degrees when
the wing was raised to increase the camber and thus the lift. Inboard
of the ailerons were a pair of small landing flaps which extended
about five degrees more than the ailerons. When the wing was lowered
after takeoff, all the surfaces returned to their normal inflight
positions, with the leading edge going to the position selected
for the cruise droop. Aerodynamically, it was actually the fuselage
that was being raised, since the wing was doing the flying.
Landing with the wing down was always possible ashore, but very
risky aboard ship, although it was done successfully on several
occasions.

The wing had a sweepback of 42 degrees at one-quarter chord and a
total area of 350 square feet. The anhedral was five degrees. The
outer wing panels folded vertically upward for carrier stowage and carried
no control surfaces. However, they still had the drooping leading
edge, providing a characteristic "dog-tooth", a chord-wise outer wing
extension to decrease instability when approaching the stall and to
minimize pitch-up tendency at high speeds.

The fuselage conformed to the Area Rule, in which the cross-section of
the fuselage was narrowed in the region of the wing. Extensive use
was made of titanium, with the rear fuselage around the afterburner
being constructed of this metal, plus extensive parts of the central
structure. The extreme nose housed the fire control radar, and the
J57 engine was fed by a oval chin-type intake located underneath the
radome. The all-flying tailplane was mounted low on the rear fuselage
and had a slight dihedral.

The variable-incidence wing obviated the need for a stalky forward
landing gear leg to keep the nose up during takeoff and landing, which
in turn make it possible to keep the gear relatively strong and of low weight. The main
landing gear members retracted forward into bays in the lower
fuselage. The aft portion of the retraction strut was covered by
a small auxiliary door. The nose landing gear member was fully
steerable and retracted rearwards into the fuselage.

A ram-air turbine was installed on a hinged panel in the right side of
the forward fuselage. When extended into the airstream, it could
provide emergency hydraulic and electrical power.

The planned armament was four 20-mm Colt Mk 12 cannon, two on each side of
the forward fuselage, with 144 rounds per gun. In addition, there was
to be provision for cheek rails immediately aft of the cockpit for a
single Sidewinder air-to-air missile, one on each side. A retractable
rocket pack housing 32 2.75-inch unguided rocket was to be installed
in the fuselage belly just underneath the air brake. The rocket pack
was supposed to be used in anti-bomber attacks or for ground attack
work.

The internal fuel supply included more than 1300 US gallons in
wing and fuselage fuel tanks.

On June 29, 1953, the Navy ordered three prototypes under the
designation XF8U-1. Bureau of Aeronautics serial numbers were 138899
through 138901. Only two of these prototypes were actually built,
138901 being cancelled before it could be built.

The first prototype (BuNo 138899) was ready for its first flight in
February of 1955. It was trucked out to Edwards AFB for its first
flight. It took off on its maiden flight on March 25, 1955, Vought
chief test pilot John Konrad being at the controls. It went
supersonic on its first flight.

The second prototype (138900) flew for the first time on September 30,
1955. It was essentially identical to the first.

138899 made 508 flights during its five years of testing. In 1960, it
was donated to the Smithsonian Institution in Washington and placed
in storage at the Smithsonian's Silver Hill facility in
Suitland, Maryland. It is reported now to be at the Seattle Museum
of Flight restoration facility in Everett, WA.
The second prototype (138900) was scrapped after
460 flights.

Serials of XF8U-1:

138899/138901 Chance Vought XF8U-1 Crusader (138901 cancelled)

Sources:

Vought F-8 Crusader, Peter Mersky, Osprey, 1981.

The Aircraft of the World, William Green and Gerald Pollinger,
Doubleday, 1965.